Soil
Soil is a natural body consisting of layers (soil horizons) that are primarily composed of minerals which differ from their parent materials in their texture, structure, consistency, colour, chemical, biological and other characteristics. It is the unconsolidated or loose covering of fine rock particles that covers the surface of the earth. Soil is the end product of the influence of the climate (temperature, precipitation), relief (slope), organisms (flora and fauna), parent materials (original minerals), and time. In engineering, soil is referred to as regolith, or loose rock material: this is the 'drift deposit' lying on top of the 'solid geology'. However, in horticulture, the term 'soil' is defined as the humic layer of topsoil, or the depth of regolith containing organic material that influences and has been influenced by plant roots and may range in depth from centimetres to many metres. Expressions such as lunar soil or Martian soil are commonly used for extraterrestrial regolith, even though there is no known biological component.
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Famous quotes containing the word soil:
“Let none admire
That riches grow in hell; that soil may best
Deserve the precious bane.”
—John Milton (1608–1674)
“Green, green is El Aghir. It has a railway station,
And the wealth of its soil has borne many another fruit:
A mairie, a school and an elegant Salle de Fetes.
Such blessings, as I remarked, in effect, to the waiter,
Are added unto them that have plenty of water.”
—Norman Cameron (b. 1905)
“Africa is a paradox which illustrates and highlights neo-colonialism. Her earth is rich, yet the products that come from above and below the soil continue to enrich, not Africans predominantly, but groups and individuals who operate to Africa’s impoverishment.”
—Kwame Nkrumah (1900–1972)